1. Field of the Invention
The present invention relates generally to methods and apparatus for sterilizing access sites. More particularly, the invention concerns a method and apparatus for sterilizing intraluminal and percutaneous access sites using ultraviolet radiation.
2. Discussion of the Prior Art
According to articles published by the Centers for Disease Control, in their Special Issue, ‘Emerging Infectious Diseases’, Vol. 7, No. 2, March-April 2001; “Nosocomial (hospital-acquired infections) bloodstream infections are a leading cause of death in the United States. Population-based surveillance studies of nosocomial infections in U.S. hospitals indicate a 5% attack rate or incidence of 5 infections per 1,000 patient-days.” With the advent of managed care and incentives for outpatient care, hospitals have a concentrated population of seriously ill patients, so rates of nosocomial infections are undoubtedly correspondingly higher.
By way of example, if 35 million patients are admitted each year to the approximately 7,000 acute-care institutions in the United States, the number of nosocomial infections—assuming overall attack rates of 2.5%, 5%, or 10%—would be 875,000, 1.75 million, or 3.5 million, respectively. If 10% of all hospital-acquired infections involve the bloodstream, 87,500, 175,000 or 350,000 patients acquire these life threatening infections each year. These are staggering numbers, especially considering this is a problem that the patients did not have when they entered the hospital.
One of the first interventions that occurs when a patient is admitted into a hospital is the placement of an intravenous access line (IV). This percutaneously-placed IV line gives the caregivers a direct path to the patient's bloodstream via a peripheral vein for rapid administration of fluids, medication or for drawing blood samples. In more serious cases, where direct access to a high blood flow supply is needed, for example, in chemotherapy delivery, temporary kidney dialysis or heart monitoring catheterization, a Central Venous Access Catheter (CVAC or Central Line) is inserted. This line is typically inserted percutaneously into a major branching vessel, frequently the subclavian vein, and then the distal segment of the catheter is directed into the superior vena cava.
Both peripheral and central catheterization procedures create an open pathway or lumen from an external access site into the bloodstream. This intraluminal access site provides an attachment point for various therapeutic or diagnostic medical devices, including, but not limited to, stopcocks, needle-less access sites, IV bags, infusion pumps, drug delivery pumps, kidney dialysis equipment, thermal dilution catheters, and the like. Unfortunately, this access site also provides an entry point for bacterial infections. Therefore, each time the access site is opened to accommodate the attachment of a medical device there is an opportunity for bacteria to enter the catheter lumen and be transferred into the bloodstream.
In addition to the contamination of the catheter lumen via the external access site, bacteria can also enter by the skin puncture and sub-cutaneous tract that is created by the catheter when the IV or CVAC is placed. Bacteria can then find their way down the outside wall of the catheter to its distal end, infecting the tract along the catheter wall as they migrate.
In an attempt to mitigate the serious problems identified in the preceding paragraphs, many prior art IV lines and CVACs use some type of molded plastic fitting at their proximal end terminated with a female Luer-lock or Luer-slip connector. These connectors must be closed by a Luer cap when not in use to prevent access site contamination. Each time the line is to be accessed, the Luer cap must be removed and discarded as it must be assumed that the outside of the Luer cap is contaminated and that once removed it is nearly impossible to prevent the male Luer configuration from touching a contaminated surface. Therefore, standard prior art infection control practice is to always replace the Luer cap whenever the line is accessed. This procedure is not only costly, but the removal and replacement process provides additional chances for bacteria to enter the lumen of the connector.
In some cases, IV access sites have been converted to needle-less access valves, which incorporate an elastomeric seal that can be opened via the tip of a male Luer connector mounted on a syringe or like device. These needle-less access valves are meant to be cleaned with an alcohol saturated swab before the valve is opened by the sterile male Luer tip of a syringe. Unfortunately, compliance with the swabbing procedures can be sporadic as it requires significant time, additional supplies and proper technique.
The thrust of the present invention is to provide a novel method and apparatus for sterilizing intraluminal and percutaneous access sites. In this regard, and by way of background, the germicidal effects of ultra violet (UV) radiation have been known since the late 19th century and in recent years the use of UV radiation has gained broad acceptance in the fields of water and air purification and has found some limited use in food processing and medical device sterilization.
UV light consists of high energy photons which occupy the 200 to 400 nanometer wavelengths of the electromagnetic spectrum. This means that UV light emits slightly less energy than soft X-ray radiation, but significantly more than visible light. UV energy does not directly kill pathogens, but rather causes a photochemical reaction within the genetic structure which inhibits the ability of the pathogens to reproduce, therefore, in effect, killing the pathogen.
The amount of energy delivered by UV light is inversely proportional to its wavelength, therefore, the shorter the wavelength, the greater the energy produced. In general, the UV light portion of the spectrum is made up of three segments; UV-A (315-400 nm), used for sun-tanning lamps, UV-B (280-315 nm) and UV-C (200-280 nm). The UV-B and UV-C regions contain wavelengths with the best germicidal action. Studies have shown that the wavelengths most effective in killing microbes are between 250-265 nm. This value corresponds nicely with the light energy output of a typical, commercially available UV-C germicidal lamp which produces most of its energy output in the range of 254 nm.